March 1 (Reuters) - Wall Street’s main indexes fell on Thursday as industrial stocks, including heavyweights Boeing and Caterpillar, took a beating on fears that potential tariffs on steel imports could hit profits.

U.S. President Donald Trump tweeted on Thursday that the U.S. steel and aluminum industries need “free, fair and smart trade”. CNBC reported that Trump will make an announcement on tariffs at 11 a.m. ET (1600 GMT).

Trump has vowed to take steps to crack down on imports of steel and aluminum and has been considering imposing hefty tariffs or quotas on imports of the metals from China and other countries under a national security law.

“I think the industrials are down as they use a lot of steel, and the uncertainty of what the tariff announcement could mean for them,” said Ryan Detrick, Senior Market Strategist for LPL Financial.

Detrick also said that investors were worried about retaliatory tariffs from China.

The S&P industrial fell 0.88 percent, with shares of Boeing and Caterpillar dipping more than 1.6 percent.

Shares of U.S. steel makers - AK Steel, US Steel Corp and Nucor - jumped on prospects of import tariffs.

At 9:48 a.m. EDT the Dow Jones industrial average was down 68.78 points, or 0.27 percent, at 24,960.42, the S&P 500 was down 5.62 points, or 0.207087 percent, at 2,708.21 and the Nasdaq Composite was down 29.13 points, or 0.4 percent, at 7,243.88. (Reporting by Sruthi Shankar and Parikshit Mishra in Bengaluru Editing by Saumyadeb Chakrabarty)